Process for treating tar acids



Patented Sept 29, 1931 UNITE STATES A E QQFFICE' CLIFFORD BAN'IA AND FRANK wn nnoiv. awes me, on PHILADELPHIA, rENusYL- VANIA, ASSIGNORS TO THE BARRETT COMIEANY, on NEW Yonx, N. Y., A. GORPORA .fIION OF NEW JERSEY rnoonss non r mamne i'ran ncxn's No Drawing.

Ourinvention pertains tothe purification oftar acids and relates more specifically to a process for the reduction of the sulfur content of tar acids.

In the coal tar industry aso-called sodium carbolate is oneofthe products] formed. This material, which is usually obtained as an aqueous solution varying in concentration over a considerable range, contains the sodium salts of'phenol, cresols, xylenols,- and similar aromatic "hydroxy compounds. Tar acid is commonly produced by adding suflicient inorganic acid to a sodium carbolate solution to'react with the 1 basic radicle and liberate the tar acids which are then removed by decantation from the resultant aqueous solution containing inorganic sodium salts'w'hich may also be present in insoluble crystalline form. The-tar acids thus liberated and decanted are usually.

treated with the amount of alkali required to remove excess inorganic acid. The crude tar acid thus produced contains, on the average, about 15% of Water and from 0.1to 0.5% of sulfur and in extremecas es has been known to contain as much as3.0% of sulfur. The presence of even the-average quantities of sulfur in tar acids is objectionable and, while various attempts have beenmade in the past to reduce the sulfurcontentof these materials, no practical process has beenavailable which --would remove. the

major portion ofthe sulfur content. W'e.

have now discovered a process whereby :as much as 85 to 95% of the sulfur content of tar acids may be removed. Our process is applicable not only to crude tar acid as usually produced in the coal tarin'dustry but to tar acids produced by other processes and .to indivdual acids such as phenols, cresols, xylenols, and similar substances.

Our process comprises the treatment of tar acids at elevated temperatures with small amountsof aromatic sulfonic acids or the 1, i J l salts of such acids, and the subsequent distillation of the treatedtar acids. :In-practise, we prefento carry/out this, treatment by digesting the tar acids in the presence of about 1% of a salt of an aromatic-sulfonic acid or inthe presence of anequivav Application filediNoveniber .24. 1928. Serial is. 321,758.

lent quantity of the free acid. Subsequently wefdistill the previously digested tar acids under diminished pressure, and as a result of this treatment We are able to remove as much -as-85 to 95%iof the sulfur originally treatment may be varied inaccordance with the tar'acid treatedand with the original sulfur content. After the digestion we prefer to distill'the tar acid under a vacuum of about twenty-seven inches of mercury, though a employed.

In the following tabulation we have indieated specific results obtained with four aromatic'sulfonic acids in our process. The crude tar acid treated was the product of the Ironton plant of the Semet-Solvay G0m pany and contained approximately 0.22% of organic sulfur. Although the distillation of'this acid under about 27 of vacuum,- Without a previous treatment with an aromatic sulfonic acid reduced the sulfur content appreciably, the sulfur remaining 'in the" distilled product was material. By dige'stingjthe crude tar acid'with 1% of a salt of an aromatic sulfonic acid for eighteen hours at about 1059. C. prior to the vacuum. distillation the following results were vobtainedz 1 l q Per cent sulfur in Material used treated and distilled acid Calcium naphthalene sulfonate. 0232 Sodium snlfanilatn I V 02]) Sodium benzene sulfonate .l .0225 Sodium cresol fl L 0199 Naphthalene beta sodium sulfonate ;0232

lesser or greater degree of vacuum may be 7 odor and of marketable quality. i

It should be understood that the speclfic examples given are merely illustrative and their. greater convenience, In place of -the specificisalts mentioned We may employ der inished;pressure, e. a 7-3- A PfWQS iQPIFllQWdQQiiQQzQfi1 116 111? filli ,QQIltent. 0i tar... acid 7 which scomprises di i are not limiting. We have found that equil t, 'qllantities'ot free sulion cacids have the same efiect as the salts but we p r e f e r to use the latter materials on account of other salts of an aromatic sulfo nic acid, though We prefer to use the alkali Or alkk line earth salts. While We prefer'to' employ about 1% of the salts or. eguiyalent propors tions of the free acids, our invention is not mite a h e?PIQ1$PIQPITQQD$ he p 'iq ic i; c eaheeni hce ni as; ost uita e e c dihera Pl at phac ie but, a erl-ctgree eit q an i y may he. e plcy d it d sir d-e Halee Pi te e. dig s she tar acid in the presence of the sulf u r e mef hs; tceee we: mainta n hemi t e a emperature, em et. cwi he isc icn empc t t reaac ch evehe ame et ught l h eiz ii etme t s usua ly Re u e n. uc ase -4 I 1 e are aware o fe the fact that others have Pro o e 116 5 mi i l ss f su nic i the hbe ei ielhh chnte f; ldehydes heets er; he n n se, f: t ie ing e t a1n acid c sulfur compounds, such as: 11161:;

- cem id. cc cec s o ar ac dsibut We. e i hetwere he vfir t sc ver a rec ss hereby prict icallyi ll. f; the sulfur present may berernoved from the a w uti bst ct al, ed tion. yie a in which; h eag mploy d n aromatic sulfonic acid or sulfonatenot ass sociated with substantial amounts of; aldeytl it ars- I a A .phevic yt n cate h al s ef. arc.- h t e i -i nic ec q ivale vquan iits c he,e ids hemse vee. ey: be s nte c eh e hly i cu Pr cessat ea-P: pen e lei is hei xp ce chtac mpc n QH iIi chro a i lich .Z a ic e i ene ic on an nc udes: cths the. free ac d. ir e pecti e} alts 7 We claimzll i I 1.' A process forthe reductionof. the sulfur content of tar acid w hichlco nprises heating said" acid in the presence of a compound containing an aromatic sulfonic radicle and in the absence of substantial amounts of aldehydes or sugars, and'distilling the resultant product under diminished-pressure. 2: A-process 'for the reduction of'the sulfur content of tar acid which comprises heat ingfsaid acid in the presence of a salt of an aromatic sulfonic acid and in the absence oi substantial amounts of aldehydes orsugars, and, distilling. the resultant .product -un gesting said acid in the presence of about 1%fof a salt of an aromatic sulfonic acid and in the absence of substantial amounts of aldehydes or sugars, and distilling the resultant product under diminished pressure. e A p cccess for the. reduction: t e S f u cgntent of tar acid Which comprises di: gesting said acid for about 18-24; hours in the pr'esence- 0-15 about 1% o-r' asalt oian aromaticsulfonic acid-and in the absence of substantial amounts of aldehydesor sugars, anddistillingthe resultant product under diminished" pressure.

5. A processiorthe reduction of theisul fur content oftar acid which comprises heathg said. acid he p zesence ct. naph hale eta cdihm; ulfcna e, and in. t e absence ..-'eiihsten ia i mcuhts c dehy es 0 f 51 g: ars, and distilling the resultant product-und m is dz1cte i u j 6, A, process for the reductionlof the; sulhe pr schccc a; cmp hd: ccntain1ng an lic tt c u cnic adi le: n in. he bsence r ofsubstantialamountsof aldehydes or sugre, an i t l g l c; esu1tan ;pncduct run.- dcr im nish d p ssunei 8. A process v for the, reduction of the, sulur, C0 lt61lt; f;t3l; cid, Whi h omprises digestingsaid acid for; about.- 18 hoursiatzabmlt Qin the presence of about l1% otnaphr halcneih tasc ium. s lfonate andin the absence of; substantial, amounts, of aldehydes or sugars, and; distilling, the resultantproduct under about; 27 ,1 inches, of vacuum 9:, 111 a; process for the, reductiQn of the sulfur content of; tar acid the. step. which comp rises heating. said acid in the; presence of-a saltgof an aromatic, sulfonicsacid andgin the absence of, substantial, amounts of alder hydes. or sugars.

10.; In a-. oroces s i012 themeduction of the sulfur content of tar acid the, step-..W-hich comprises digesting said, acid; for, about; 18;- 2ihours in, the presence of: a-compound; con; taining, an;;ar omatic sulfon-ic radicleiandtin. the absence oi"v substantial amounts of. aldehydeson sugars...

V 1. n .a process for-gthel reduction of; the sulfur content; of; taracidi'the step: which comprises digesting said acid in the. presence of; naphthalene beta. sodium sulfonate and in the A absence ofsubstantial amounts of aldehydes or" sugars. i 12. Ina process fer-the reduction of: the sulfur content of tar acid the step wllich comprises digesting said acid for about 18- 24 hours in the presence of about 1% of naphthalene beta sodium sulfonate' and in the absence of substantial amounts of a1de-' hydes or sugars.

13. In a process for the reduction of the t sulfur content of tar acids the step which comprises digesting said acid in the presence of a compound containing an aromatic sulfonic radicle and in the absence of substantial amounts of aldehydes or sugars;

In testimony whereof We afiix our signatures.

CLIFFORD BANTA. FRANK WELDON HIGHTOWER. 

